与 across 和 .names 发生变异："glue cannot interpolate functions into strings" 错误

Question

我有不同选区候选人的选举结果。来源有每个候选人的票数和每个选区的总票数。我想为每个候选人在每个地区获得的选票百分比添加变量。

我已经成功地使用 mutate 和 across 将投票计数替换为百分比，但是在尝试使用 .names 参数创建新变量时出现错误（即我希望获得新变量，cand1_pct、cand2_pct、...）。

library(tidyverse)
df <- data.frame(district = 1:3,
                 cand1 = c(12, 2, 14),
                 cand2 = c(2, 6, 23),
                 cand3 = c(3, 16, 2),
                 total = c(17, 24, 39))
df %>% 
  mutate(across(2:4, ~ .x/total*100))
#>   district     cand1    cand2     cand3 total
#> 1        1 70.588235 11.76471 17.647059    17
#> 2        2  8.333333 25.00000 66.666667    24
#> 3        3 35.897436 58.97436  5.128205    39
  
df %>% 
  mutate(across(2:4, ~ .x/total*100, .names = "{.col}_pct"))
#> Error: Problem with `mutate()` input `..1`.
#> x glue cannot interpolate functions into strings.
#> * object '.col' is a function.
#> i Input `..1` is `across(2:4, ~.x/total * 100, .names = "{.col}_pct")`.

^{由 reprex package (v0.3.0)}

于 2020-08-12 创建

我首先认为这是我对 across 和 .names 应该如何工作的误解，但是当我使用 across vignette 我犯了同样的错误。我在我的本地机器和 RStudio 云上都试过了。 dplyr 版本 1.0.1.

library(dplyr)

iris %>%
  group_by(Species) %>%
  summarise(across(starts_with("Sepal"), mean, .names = "mean_{.col}"))
#> Error: Problem with `summarise()` input `..1`.
#> x glue cannot interpolate functions into strings.
#> * object '.col' is a function.
#> i Input `..1` is `across(starts_with("Sepal"), mean, .names = "mean_{.col}")`.
#> i The error occurred in group 1: Species = "setosa".

^{由 reprex package (v0.3.0)}

于 2020-08-12 创建

Answer 1

根据?across，不是.col，只是col

.names - The default (NULL) is equivalent to "{col}" for the single function case and "{col}_{fn}" for the case where a list is used for .fns.

library(dplyr)
df %>% 
   mutate(across(2:4, ~ .x/total*100, .names = "{col}_pct"))
#  district cand1 cand2 cand3 total cand1_pct cand2_pct cand3_pct
#1        1    12     2     3    17 70.588235  11.76471 17.647059
#2        2     2     6    16    24  8.333333  25.00000 66.666667
#3        3    14    23     2    39 35.897436  58.97436  5.128205

Answer 2

...情况发生了变化。

根据最新dplyr 1.0.2中的?across，现在建议使用.col，而不是col。

.names - A glue specification that describes how to name the output columns. This can use {.col} to stand for the selected column name, and {.fn} to stand for the name of the function being applied. The default (NULL) is equivalent to "{.col}" for the single function case and "{.col}_{.fn}" for the case where a list is used for .fns.

可以在此处找到更多信息和用例：

与 across 和 .names 发生变异："glue cannot interpolate functions into strings" 错误

mutate with across and .names: "glue cannot interpolate functions into strings" error

r

dplyr

across